Bi-annual US dollars 1987-06-30 0 1987-12-31 0 1988-06-30 0 1988-12-31 0 1989-06-30 0 1989-12-31 0 1990-06-30 0 1990-12-31 0 1991-06-30 0 1991-12-31 0 1992-06-30 0 1992-12-31 0 1993-06-30 0 1993-12-31 38 1994-06-30 31 1994-12-31 161 1995-06-30 47 1995-12-31 137 1996-06-30 17 1996-12-31 159 1997-06-30 169 1997-12-31 552 1998-06-30 195 1998-12-31 234 1999-06-30 101